The present invention relates generally to a navigation system for a vehicle and method therefor.
More specifically, the present invention relates to navigation systems and methods employing a graphic display unit on which a roadmap and the current position of the vehicle are displayed, so that the driver of the vehicle can drive the vehicle in accordance with a present travel course displayed on the display unit.
This kind of navigation system for vehicles is disclosed in a Japanese patent application Unexamined Open No. Sho 58-112199 published on July 4, 1983.
In the above-identified Japanese patent application document, a series of guidance information necessary to guide the vehicle to a final destination along a preset route of travel is displayed on a screen of a display unit so as to enable the driver to drive the vehicle in accordance with the preset route of travel displayed on the display unit to reach the final destination.
In this kind of navigation system, the driver drives the vehicle on an arbitrary route until the vehicle reaches a first intersection (hereinafter referred to as a start intersection) at which the guidance of vehicle along the preset route of travel is initiated and thereafter the driver can drive the vehicle along the preset route of travel to arrive at the final destination.
However, there is a drawback in the above-described navigation system that in a case where the driver has little or no knowledge of information on roads in a region around the start intersection, the driver often mistakes a road radiated from the start intersection and at which the vehicle is initially to start the travel along the preset course since the driver cannot find such a start road.